The invention relates to anti-theft devices for use with vehicles. Reference is made to the copending application entitled Alarm Device, filed Dec. 5, 1977, in the name of Mark R. Cleary, Ser. No. 856,960 (now issued as U.S. Pat. No. 4,174,516).
As pointed out in the aforementioned application, numerous devices have been devised with the object of protecting automobiles from being broken into by unauthorized people. These devices have had numerous failings, such as continuous sounding of an alarm after activation until the battery wears down or the device is manually disengaged. Inability to automatically rearm, and ease of circumvention of the triggering circuits should the intruder remain in the vehicle, were common failings of those devices which did automatically disengage. The device of the aforementioned application provided a two-tone siren alarm for automobiles that was responsive to a variety of triggers, such as transient variances in potential of the automobile electric systems and signals from pressure switches and the like. The alarm automatically terminated after a set period and rearmed, allowed for a brief delay before arming to permit an authorized user to leave the car without triggering the alarm, allowed for a brief delay before sounding after triggering to permit an authorized user to disarm the alarm, and tended to reduce wear on the battery.
The foregoing notwithstanding, further attention can always be paid to developing improved anti-theft devices. Minimizing user involvement with such a device, both during installation and during use, would tend to reduce human error and maximize effectiveness of such devices.